- Provides Update on RNAi Platform Innovations, Including New Data on
CNS and Ocular Delivery Expected to Support Robust and Broadly
Distributed Target Gene Silencing with Bi-Annual and Possibly Less
Frequent Dosing Regimens –

Alnylam
Pharmaceuticals, Inc. (NASDAQ:ALNY), the leading RNAi therapeutics
company, announces it is hosting its R&D Day in New York City today.
During the event, the Company plans to discuss its pipeline goals for
2019, focusing on five late-stage investigational programs advancing
toward potential commercialization. These programs include the Company's
wholly owned programs: givosiran for the treatment of acute hepatic
porphyria (AHP), lumasiran for the treatment of primary hyperoxaluria
type 1 (PH1), and vutrisiran (voo-TREE-si-ran, formerly
ALN-TTRsc02) for the treatment of ATTR amyloidosis. The Company will
also discuss commercial execution with ONPATTRO™ (patisiran).

Alnylam also announces today a number of commercialization and pipeline
updates. In early January 2019, the Company expects to pre-announce
global product revenues for ONPATTRO and number of patients on
commercial drug for the fourth quarter of 2018. The Company announces
today that it has filed regulatory submissions for ONPATTRO in Canada
and Switzerland, and expects regulatory decisions in 2019. In addition,
Alnylam announces initiation of a rolling submission of an NDA to the
FDA for givosiran and initiation of the HELIOS-A pivotal Phase 3 study
of vutrisiran in patients with hATTR amyloidosis. Alnylam will also
discuss multiple earlier stage clinical and pre-clinical programs and
RNAi platform innovations, including its progress on extra-hepatic
delivery of RNAi therapeutics. As part of this update, the Company today
announces that its first central nervous system (CNS)-targeted
development candidate will be ALN-APP, an investigational RNAi
therapeutic targeting amyloid precursor protein (APP) for the treatment
of cerebral amyloid angiopathy (CAA) associated with intracerebral
hemorrhage.

"In the coming year, we plan to continue our commercial execution for
ONPATTRO, bringing this much needed medicine to eligible patients around
the world, including an upcoming launch expected in Japan, assuming
regulatory approval, and potential launches in other global markets. In
addition, our continued execution, together with our partners, on our
clinical pipeline of five late-stage investigational programs is poised
to bring potential approvals of new RNAi therapeutics essentially on an
annual basis in each of the coming years, with three expected Phase 3
program data readouts in 2019 alone and two potential NDA filings, one
in mid-2019 and one at or around year-end 2019, assuming positive
results," said John Maraganore, Ph.D., Chief Executive Officer of
Alnylam. "We believe we are at an unparalleled stage of our company's
growth, with a large number of opportunities with transformative
potential for patients across both rare and common diseases. We expect
our progress will enable achievement of our ‘Alnylam 2020' vision of
becoming a multi-product, global, commercial-stage biopharma company
with a deep and sustainable clinical pipeline and a robust research
engine for future innovation and patient impact."

Givosiran, an investigational RNAi therapeutic in development for
the treatment of acute hepatic porphyria (AHP). Alnylam plans to:

Report topline results from the ENVISION Phase 3 trial in early 2019.

Complete submission of an NDA to the FDA in mid-2019.

File a marketing authorisation application (MAA) with the European
Medicines Agency (EMA) in mid-2019.

Lumasiran, an investigational RNAi therapeutic in development for
the treatment of primary hyperoxaluria type 1 (PH1). Alnylam plans to:

Complete enrollment in the ILLUMINATE-A Phase 3 study in mid-2019.

Initiate ILLUMINATE-B and -C Phase 3 studies in mid-2019.

Report topline results from the ILLUMINATE-A Phase 3 study in late
2019.

Alnylam also plans to support The Medicines Company's continued efforts
with respect to the ORION Phase 3 studies of inclisiran, an
investigational RNAi therapeutic targeting PCSK9 in development for the
treatment of hypercholesterolemia. Specifically, The Medicines Company
has guided to:

File an NDA in the U.S. at or around year-end 2019, assuming positive
Phase 3 results.

Alnylam also plans to support Sanofi's continued efforts in advancing
fitusiran, an investigational RNAi therapeutic in development for the
treatment of hemophilia.

In addition, the Company plans to continue advancement of its
earlier-stage clinical pipeline, including a Phase 2 study of
cemdisiran, a Phase 1/2 study of ALN-AAT02, and, together with its
partner Vir Biotechnology, a Phase 1/2 study of ALN-HBV02 (also known as
VIR-2218), investigational RNAi therapeutics in development for the
treatment of IgA nephropathy, alpha-1 anti-trypsin deficiency-associated
liver disease, and hepatitis B virus (HBV) infection, respectively. The
Company expects clinical data readouts from each of these programs in
2019. Alnylam also plans to file one or more new clinical trial
applications (CTA) in 2019, including for ALN-AGT, an investigational
RNAi therapeutic targeting angiotensinogen for the treatment of
uncontrolled hypertension. Alnylam will also continue to build on its
progress with extra-hepatic delivery, with a newly selected CNS-targeted
development candidate, ALN-APP, an investigational RNAi therapeutic for
the treatment of CAA.

The Company's R&D Day will be held today, December 6, 2018 from 8:00 am
to 1:00 pm ET at the Westin New York at Times Square in New York City
and will include a live video stream on the Investors section of the
Company's website, www.alnylam.com.
A replay will be available on the Alnylam website within 48 hours after
the event. Presentations showcased during the event will be featured on Capella.

About RNAiRNAi (RNA interference) is a natural cellular
process of gene silencing that represents one of the most promising and
rapidly advancing frontiers in biology and drug development today. Its
discovery has been heralded as "a major scientific breakthrough that
happens once every decade or so," and was recognized with the award of
the 2006 Nobel Prize for Physiology or Medicine. By harnessing the
natural biological process of RNAi occurring in our cells, a new class
of medicines, known as RNAi therapeutics, is now a reality. Small
interfering RNA (siRNA), the molecules that mediate RNAi and comprise
Alnylam's RNAi therapeutic platform, function upstream of today's
medicines by potently silencing messenger RNA (mRNA) – the genetic
precursors – that encode for disease-causing proteins, thus preventing
them from being made. This is a revolutionary approach with the
potential to transform the care of patients with genetic and other
diseases.

About Alnylam PharmaceuticalsAlnylam (NASDAQ:ALNY) is
leading the translation of RNA interference (RNAi) into a whole new
class of innovative medicines with the potential to transform the lives
of people afflicted with rare genetic, cardio-metabolic, hepatic
infectious, and central nervous system (CNS) diseases. Based on Nobel
Prize-winning science, RNAi therapeutics represent a powerful,
clinically validated approach for the treatment of a wide range of
severe and debilitating diseases. Founded in 2002, Alnylam is delivering
on a bold vision to turn scientific possibility into reality, with a
robust discovery platform. Alnylam's first U.S. FDA-approved RNAi
therapeutic is ONPATTRO™ (patisiran) lipid complex injection available
in the U.S. for the treatment of the polyneuropathy of hereditary
transthyretin-mediated (hATTR) amyloidosis in adults. In the EU,
ONPATTRO is approved for the treatment of hATTR amyloidosis in adults
with stage 1 or stage 2 polyneuropathy. Alnylam has a deep pipeline of
investigational medicines, including five product candidates that are in
late-stage development. Looking forward, Alnylam will continue to
execute on its "Alnylam 2020" strategy of building a multi-product,
commercial-stage biopharmaceutical company with a sustainable pipeline
of RNAi-based medicines to address the needs of patients who have
limited or inadequate treatment options. Alnylam employs over 1000
people worldwide and is headquartered in Cambridge, MA. For more
information about our people, science and pipeline, please visit www.alnylam.com
and engage with us on Twitter at @Alnylam
or on LinkedIn.

Alnylam Forward Looking StatementsVarious statements in
this release concerning Alnylam's future expectations, plans and
prospects, including, without limitation, Alnylam's views with respect
to the potential for RNAi therapeutics, including vutrisiran, givosiran,
lumasiran, inclisiran, fitusiran, ALN-AAT02, ALN-HBV02, cemdisiran, and
ALN-APP, its plans for additional regulatory filings and product
launches for ONPATTRO in 2019, including launches in Japan, Canada and
multiple EU countries, its expectations about the announcement of plans
for potential expansion of the ONPATTRO label, its plans to continue
enrollment in its HELIOS-A Phase 3 study of vutrisiran in hATTR
amyloidosis throughout 2019 and initiate its HELIOS-B Phase 3 study in
ATTR amyloidosis patients with cardiomyopathy in late 2019, its
expectations regarding the timing for completion of a rolling NDA
submission with the FDA and submission of a MAA for givosiran and the
reporting of complete topline results, its expectations regarding the
potential timing of ILLUMINATE-A Phase 3 topline study results for
lumasiran in late 2019 and its plans to initiate the ILLUMINATE-B Phase
3 study of lumasiran, its plan to initiate the Phase 1/2 study for
ALN-AAT02 in alpha-1 liver disease, expectations regarding the timing of
study completion and data readouts for inclisiran by The Medicines
Company during 2019 and the potential filing of an NDA if such data are
positive, its plans to support Sanofi's continued efforts in advancing
fitusiran for the treatment of hemophilia, and expectations regarding
the progress of multiple early stage clinical programs and its first
CNS-targeted development program, ALN-APP, and expectations regarding
its "Alnylam 2020" guidance for the advancement and commercialization of
RNAi therapeutics, constitute forward-looking statements for the
purposes of the safe harbor provisions under The Private Securities
Litigation Reform Act of 1995. Actual results and future plans may
differ materially from those indicated by these forward-looking
statements as a result of various important risks, uncertainties and
other factors, including, without limitation, Alnylam's ability to
discover and develop novel drug candidates and delivery approaches,
successfully demonstrate the efficacy and safety of its product
candidates, the pre-clinical and clinical results for its product
candidates, which may not be replicated or continue to occur in other
subjects or in additional studies or otherwise support further
development of product candidates for a specified indication or at all,
actions or advice of regulatory agencies, which may affect the design,
initiation, timing, continuation and/or progress of clinical trials or
result in the need for additional pre-clinical and/or clinical testing,
delays, interruptions or failures in the manufacture and supply of its
product candidates, obtaining, maintaining and protecting intellectual
property, Alnylam's ability to enforce its intellectual property rights
against third parties and defend its patent portfolio against challenges
from third parties, obtaining and maintaining regulatory approval,
pricing and reimbursement for products, progress in establishing a
commercial and ex-United States infrastructure, successfully launching,
marketing and selling its approved products globally, Alnylam's ability
to successfully expand the indication for ONPATTRO in the future,
competition from others using technology similar to Alnylam's and others
developing products for similar uses, Alnylam's ability to manage its
growth and operating expenses, obtain additional funding to support its
business activities, and establish and maintain strategic business
alliances and new business initiatives, Alnylam's dependence on third
parties for development, manufacture and distribution of products, the
outcome of litigation, the risk of government investigations, and
unexpected expenditures, as well as those risks more fully discussed in
the "Risk Factors" filed with Alnylam's most recent Quarterly Report on
Form 10-Q filed with the Securities and Exchange Commission (SEC) and in
other filings that Alnylam makes with the SEC. In addition, any
forward-looking statements represent Alnylam's views only as of today
and should not be relied upon as representing its views as of any
subsequent date. Alnylam explicitly disclaims any obligation, except to
the extent required by law, to update any forward-looking statements.

With the exception of ONPATTRO (patisiran), none of Alnylam's
investigational RNAi therapeutics have been approved by the U.S. Food
and Drug Administration, European Medicines Agency, or any other
regulatory authority and no conclusions can or should be drawn regarding
the safety or effectiveness of such investigational therapeutics.